Expanding the Silicon Photonics Portfolio With Silicon Nitride Photonic Integrated Circuits

TLDR

Silicon photonics, dominated by the silicon‑on‑insulator platform, has expanded beyond optical communications into sensing and spectroscopy, but silicon’s lack of visible‑wavelength transparency motivates exploration of alternatives such as silicon nitride, which offers moderate index contrast and CMOS‑compatible fabrication. This paper examines the advantages and challenges of silicon‑on‑insulator and silicon nitride photonic platforms. The authors illustrate these trade‑offs using dispersive spectrometers as a representative application for both material systems.

Abstract

The high index contrast silicon-on-insulator platform is the dominant CMOS compatible platform for photonic integration. The successful use of silicon photonic chips in optical communication applications has now paved the way for new areas where photonic chips can be applied. It is already emerging as a competing technology for sensing and spectroscopic applications. This increasing range of applications for silicon photonics instigates an interest in exploring new materials, as silicon-on-insulator has some drawbacks for these emerging applications, e.g., silicon is not transparent in the visible wavelength range. Silicon nitride is an alternate material platform. It has moderately high index contrast, and like silicon-on-insulator, it uses CMOS processes to manufacture photonic integrated circuits. In this paper, the advantages and challenges associated with these two material platforms are discussed. The case of dispersive spectrometers, which are widely used in various silicon photonic applications, is presented for these two material platforms.